feature: hey backdate <event_id | last> <count> <hours|minutes>

[masukomi]

hey backdate <event_id | last> <count> <hours|minutes>

should backdate the specified event by the specified amount. Going in the opposite direction should not be required. E.g. "Bob's totally going to interrupt me in an hour. I know it!"

as with other things you should be able to enter the id of the event or "last"

it will then alter the created_at of the event by the specified number of hours or minutes.